Pork bellies are injected with a curing solution, called pickle, in order to make bacon. Conventional injection machines have a vertically reciprocating crosshead with multiple needles. The crosshead is typically driven by a crank. A normal conveyor carries the bellies under the needles and is moved intermittently ahead when the needles are removed so that a pattern of intermittent injections are made in the bellies as they incrementally move under the needles, and are then injected as they become stationary between intervening movements.
The needles project down through to the bottom of the belly as the belly lays on the stationary conveyor and then the needles stop and reverse direction and return upward out of the bellies. The needles and crosshead continue their upward stroke above the bellies while the conveyor moves forward to place the belly for another injection. Also, as the needles clear the top of the bellies, the stripper plate that held the bellies in place is raised by the crosshead to allow movement of the belly under the needles.
The pump for the pickle is usually a positive displacement pump and pumps pickle through the needles at a constant rate. When the needles are out of the bellies, the pickle is usually allowed to continue to run from the needles and is collected underneath the bellies and re-filtered and fed back into the reservoir to be used again.
Such fluid injection machines for meat products have been used for many years, but they have several negative factors, one of which is very detrimental. The distribution of pickle throughout the belly should be as uniform as possible. That means that every cubic centimeter should have the same amount of pickle throughout the entire belly. When the crosshead and needles are moved up and down by a crank mechanism, the velocity of the needles is constantly changing from zero to maximum and back to zero, etc. as the needles move up and down in the belly. With a constant flow pump, the bellies get more or less pickle per cubic centimeter, depending on the velocity of the needles in moving into and out of the meat.
Stated differently pickle is generally supplied into the injector head by a positive displacement pump with constant flow rate. The needles driven by a rotational crank travel at a variable speed through the thickness. When needles are near either top or bottom position, the needle traveling speed is close to zero, while at the middle stroke needles travel at the highest speed. More pickle is injected per unit length of travel when needles are moving at slow speed and less pickle is injected at high speed. It is highly desirable to inject equal amount of pickle per unit length of thickness to achieve the best quality of injection.
Another negative feature of past injection machines is the bad inertial forces that build up in the conveyor as it starts and stops. The conveyor with its load of bellies must be stopped when the needles are injecting pickle into the belly. When the needles are out of the belly, the conveyor must move ahead to place the belly in position for another injection by the needles. This arrangement necessitates continual starting and stopping of the conveyor with its heavy load of bellies, and this is very undesirable. Since the injector head moves in a nearly vertical direction, the conveyor has to stop during the injection process to allow needles to penetrate into and out of pork bellies without introducing the lateral motion. This intermittent motion of the conveyor accelerates and decelerates pork bellies and creates inertia forces to shake the whole injector machine. The noise level generated from injection operation will be greatly reduced if the conveyor has a continuous motion.
Another problem with past injectors is the flow of pickle when the needles are out of the bellies. Some injectors allow the pickle to continue to run out of needles where it is collected and returned to the reservoir. Other injectors start the flow after the needles start into the bellies and shut off the flow as the needles are coming out of the bellies. This starting and stopping of the flow is an inertial problem. Also, letting the pickle flow continuously and catching it and returning it to the reservoir is undesirable.
Therefore, it is a principal object of this invention to inject meat products with a fluid as the meat moves continuously through a fluid injection station without having to stop the meat product while it is being injected.
A further object of the invention is to inject a meat product with a battery of needles by pumping the fluid constantly, with fluid going into the injecting needles while they are in the meat product, and with the fluid bypassing the needles and returning to the fluid reservoir when the needles are out of the product.
A further object of this invention is to create a uniform pickle injection through the thickness of pork bellies by using a double action piston pump with its output flow rate matching the velocity of the injecting needles.
A further object of this invention is to eliminate the inertia load created by the intermittent motion of the conveyor and pork bellies placed on the conveyor by using a continuously moving conveyor to carry pork bellies.
A further object of this invention is to develop a driving mechanism so that the lateral motion of the injector head during the injecting process matches the linear speed of the conveyor and the injector head is returned back to its beginning position for next cycle while needles are out of pork bellies.
A further object of this invention is to control the pickle flow into the injecting needles only during the injecting process and to direct the pickle flow back into reservoir without starting or stopping the piston pump and pickle flow.
A further object of this invention is to adjust the output flow rate of the piston pump to achieve desired percentage of pickle injection.
The injector machine of this invention includes a system of allowing the conveyor to run continuously at a constant speed, so that the conveyor with the weight of the bellies is moving at a constant rate rather than an intermittent motion that causes undesirable inertial forces. Because the conveyor and the bellies are moving at a constant speed, the crosshead with the needles must also move forward with the conveyor and bellies whenever the needles are pierced into the bellies. This means that the crosshead and needles must be moving forward with the bellies at the same speed anytime that the needles are being inserted or pulled out of the bellies. Then as the crosshead and needles continue their upward stroke above the bellies, the crosshead is moved back to the starting position and the needles move down to the bellies. The crosshead and needles still continue to move by a crank action that starts from zero velocity at the upper center of the stroke and gradually increases to a fast velocity in the middle of the stroke, and then again decelerates to zero at the bottom of the stroke, and from there accelerates and decelerates again to the top position of the stroke. This arrangement allows for the conveyor with the bellies to move at a continuous, constant velocity. While the needles are inserting and withdrawing, they inject pickle both on the way in and the way out, as long as they are in the belly.
To facilitate this coordinated motion of the bellies and the needle crosshead, a long pitman arm is located at each end of the crosshead and is driven in a reciprocating motion from a crank. Then as the crosshead with the needles is going up and down, a cam works against the pitman arms on the ends of the crosshead to move the crosshead back and forth as needed to assure that the needle speed corresponds with the belly speed whenever the needles are in the bellies. The crosshead and needle assembly are made as light as possible to give a small mass being reciprocated back and forth as the crosshead is going up and down.
Bellies are a combination of fat and lean, but it is desirable to have the same amount of pickle (brine solution) in each cubic centimeter of belly. This would be a simple matter if the needles were moving at a constant speed as they descend and ascend in and out of the bellies. Crank action is more practical for a reciprocating motion like this, but in that case the needles are changing velocity constantly. The constant change in velocity of the needles means that the time that a needle is passing through each vertical centimeter will constantly be changing from fast to slow to fast to slow. Thus, the flow of pickle should also change accordingly. This invention accomplishes this goal by using a double action piston type pump where the piston is controlled or synchronized by the same drive as the needles. That piston pump is timed exactly with the needle crank, so that the action of the piston pump corresponds with the timing of the crank action that drives the needles. This assures that the flow of pickle from the pump at any instant of time will correspond with the velocity of the needles at that same instant of time. Therefore, the amount of pickle injected into every portion of the belly will be constant and uniform throughout the bellies in spite of the variation in velocity of the needles due to the crank action. This is a very important principle because it allows for the use of an efficient crank action to reciprocate the needles and still gives a flow of pickle that corresponds to the velocity of the needles at all times.
The pump is not a constant flow but rather a piston pump which is driven by a crank mechanism. This piston crank mechanism is timed with the needle crank mechanism so that when the needles are moving fast through the bellies, the piston crank mechanism is moving the piston of the pump at a comparable fast velocity. This assures that the amount of pickle flowing through the needles is always comparable to the velocity of the needles and is therefore uniformly distributed evenly through the belly in spite of the varying velocity of the needles. This feature of this invention eliminates the biggest objection to the past injectors as mentioned above.
The machine has a switch valve that is controlled by the stripper plate so that as the needles come out of the bellies and the stripper plate begins to rise off the bellies, the pickle from the pump is switched by the stripper plates from the crosshead and needles to the reservoir until the needles are starting into the bellies again, and are-ready for the pickle to flow through the needles again into the bellies. At this time, the switch valve switches the pickle back to the needles instead of the reservoir. Switching the pickle from the pump back and forth between the needles and the reservoir allows for a continuous flow from the pump and maintains the velocity relationship of the flow between the pump and the needle velocity.
In summary, the injector machine of this invention includes:
1. A conveyor running continuously at a constant speed to eliminate the inertia load while carrying the pork bellies through the injection process.
2. A double action piston pump synchronously driven by the same crank mechanism as the injector head so that the output flow rate of the pickle matches the motion of injecting needles to achieve uniform pickle injection through the thickness of pork bellies.
3. A crank driving mechanism and a cam-spring control mechanism to move the injector head in both vertical and lateral directions simultaneously. The vertical motion of the injector head accomplishes the injection process with needles penetrating into and retracting from pork bellies; the lateral motion of the injector head matches the forwarding motion of the conveyor during the injection process and returns the injector head back to its beginning position while needles are out of bellies.
4. A directional valve switch to control pickle flowing either into injecting needles or reservoir. During the injection process, the movement of the stripper plate relative to the tip of needles directs the pickle flowing into injecting needles. When needles are out of meat, the stripper plate actuates the valve to direct pickle back to reservoir.